1. Field of the Invention
The invention relates to etching a silicon layer, and more particularly to a method of etching a silicon layer to avoid non-uniformity.
2. Description of the Related Art
Silicon has been widely used in the semiconductor field, not only for semiconductors also for thin film transistor liquid crystal displays (TFT LCD).
Normally, semiconductors are fabricated by series process comprising cleaning, deposition, photolithography, etching. However, it is difficult to acquire a silicon layer with a uniform thickness after etching. Conventionally, after patterning the silicon layer, residue of SixOyClz remains from the reaction of the etching agent comprising hydrogen halide (HX), such as HF, HCl, and HBr, and the silicon layer, formed on the sidewalls of the patterned silicon layer 102a, as shown in FIG. 1A. The residue 106 of SixOyClz is so stable, such that residue serving as a hard mask can protect the silicon from etching after removing the photoresist layer 104, as shown in FIG. 1B. Thus, sidewalls of the patterned silicon layer 102a are thicker than the other parts of the patterned silicon layer 102a. It is thus difficult to reduce the patterned silicon layer 102a uniformly using etching agents comprising hydride halogen.